Stress-balancing splice bar



Dec. 21 1926.

B: G, BRAINE s-Sheet 2 d Nov. 28. 1925 m E` ,WM a B 31m/manto@ named Dec. 21, 1926.

,F.UNITEDA STATES VPATENT OFFICE.

BANCROFT G.v BRAIN, F MONTCLAIR, NEW JERSEY, ASSIGNOR TO THE RAILFJ'OINT COMPANY, 0F NEW YORK, N. Y.,

A CORPORATION 0F NEW YORK.

STRESS-BALANCING SPLICE BAR.

for reissue filed November This invention relates to a splice bar construction involving a novel distribution of metal whereby a substantial lightening of the bar may be obtained, and at the same l time the whole structure materially strengthened as to itsJ stress-resisting capacity and axis are of 'substantially equal area and modulus.

Accordingly, it is the, purpose of the present invention to so shape the splice bar sec? tion in its head, web and foot member, and l to so relate the metal distribution in the shape above and below a. neutral axis or middle. line, that the physical properties of the effective unsymmetrieal parts of the bar at the top and at the bottom will be almost, if not quite, balanced, whereby the centers of gravity and the centers of stress of the top and bottom partsof the bar 'will be so locatedfthat the barwill be substantially balanced as to its physical properties, and particularly balanced statically and as to stresses.

vVith thesev and other objects in view which will be apparent to those skilled in this art as the nature of the invention is better understood, the same consists in the novelY features hereinafter more fully described, iilustrated and claimed: and while the invention is susceptible of embodiment in various modifications of any particular shape, a preferred and practical embodi- "mentthereof is shown in the accompanying drawings, in which Figure l is a cross-sectional 4view of a respectively above and below the horizontal Application 3, 1926. Serial No. 146,268.

splice bar planned arid constructed aecordy ing to the present invention and shown tit` vting the iishing space of a. rail.

Figure 2 is a similar view of the same splice bar illustrating the location of the i centers of gravity ofthe head and foot portions of the bar respectively above and belowl a neutral axis or middle line; the center of', gravity for the full baralso-,being indicated.

Figure 3 is a similar view of the same barshowing the location of the center .lines'of- 60 stress of the head and footportions'of the bar with reference to a neutral axis o1 n1;i`d' dle line. Y. f

Figure 4 is a similar View of the sainebar I.

showing, by dotted lines, a, form ofspiice 5 bar heretofore used which'- has been replaced by the improved bar shownin full section-.- the' two bars being accurately superiinp'sed to illustrate the substantial'departure frm the dotted line shape.

A primary feature of the invention of practical importance is that of producing a splice bar shape having a novel distribution otlmetal particularly in the head, web, and

footpmembers in their relation to an en- V larged and widened head, that will provide an approxir'nate balancing of the barv as to the areas respectively above and below a4 neutral axis. or middle line, and also statically balanced. as to stresses, thereby necessarily involvingl a. substantial balancing of the physical properties of the .effective unsymmetrical parts of the bar-respectively above and below the said neutral axis or middle line. Accordingly, in laying out a B5 splice bar shape following the principles of the present invention to obtain a balancing of stresses in the statically balanced portions, the important factors to be calculated and employed are the moment of inertia,the 00 section modulus, thestatic moment, as well as the area. Furthermore, it is important to the successful carrying out of the invention that the center of gravity of the head part vot' the bar shall'be, at substantially the same 95 distance above the neutral axis or middle line as the center of gravity for theV footmember of the bar is below the said axis or middle line,.and that the center line of stress' of the head part of the bar shall be at substantially the same distance above the neutral axis or middle line as the center line.

of stress for the foot part of the bar is befY low the said .axis or middle line.4

Certain denitions are important to bearl in mind in obtaining a full understanding I of the present inventionparticularly as to lof rotation to the center of gravity of that area, plus the moment -of inertia of that area about its neutral axis parallel to theassumed axis of rotation; while the static moment of a particular area is the product of that area multiplied by the distance from an assumed axis of rotation to its neutral axis parallel to the assumed axis of rotation.

The section modulus of a section'is'a coefficient or measure of a force. and in dealing with metal shapes of the splice bar type the section modulus thereof is in effecta modulus of rupture, that is, the measure of the force tending to make a fracture or rupture and is directly relatedto the moment of in'- ertia. The calculation for the .section modu lus of a splice bar section is made 'according to the formula of .dividing the moment of inertia by the distance from the axes respectively to the extreme top and bottom fibres of the section, thus obtaining the topi-modulus of the section and Vthe bottom modulus of the section.

With reference to Alocating the center of stress or pressure of the whole upper and lower halvesof the bar, or the corresponding upper and lower unsymmetrical portions, that phase of the invention is directly related to the moment of inertia and the static moment, that is, `to the inertia static ratio. In explanation of that feature of the invention it is to be noted that the center of stress or pressure of either of the portions above or below the neutral axis orL middle line `of the bar.. as a whole, is obtained by dividing the moment of inertia ofl the portion to be considered by the static moment of the portion to be considered; and` itis one of the practical and important features of the present invention to pr0.

. vide a splice bar having a proportional distribution of metal in the whole upper and lower halves of the bar, and in the coprespondingl upper and lower unsymmetrical portions to provide a substantial equivalence between the inertiastatic ratios thereof, whereby the centers of stress or pressure .to area, and also as to stress. there is taken of said corresponding portions are at substantially the same distances respectively above and below the approximate neutral axis or middle line of the bar.

As the foregoing factors enter into the .Successful carrying out of the invention and involveboth the first and second moments of a bar, it is also important to note that in balancing the bar approximately as Y Yinto consideration the well known fact that the effect of a load acting on any piece ofy construction is a change of form or dimension of/the piece and this change ofform 'or dimension is called strain; and the combination of internal forces whichV are calledinto play in the section to resist or balance the load is called stress. Therefore, in carrying out the invention to `proi vide for a balancing of stresses at equal distances above and below a neutral axis or middle line the upper and lower sections of the bar have effective Zones of metal of the same or substantially the same area, designated l, 2 and 3 in the example given on Fig. 4 of the drawings, at equal or substantially equal distances from a neutral axis or middle line designated A in the drawings. In obtaining that result, namely, to provide the bar sections with zones of metal of substantially the same area `at equal distances from the axis or middle line it will be understood that this has particular reference to the unsymmetrical parts .of the bar. because inA a web of uniform width at and adjacent the neutral axis the areas of the metal in the uniform part of the web necessarily will have the same area at. equal distances above and' below the axis. But` regardless of that dis-v tinction it is important in carrying out the invention that the substantially equal areas or zones of metal at equal distances from Athe axis shall not only be of approximately thc same area and therefore approximately bal anced as to'area, but al Vmust be substantially balanced as to all'of their effective physical properties, and furthermore, as to lll() their centers of gravity and cente'i` lines of.

stress.

The feature of having-the effective zones balancing ofthe effective physical proper- ,ties of such zones of metal results in the desirable eifectof advantageously 'locating the centers of gravity for the upper and lower unsymmetrical parts of the bar. This is shown in Fig. 2 ofY the drawingswhiclr125 bears theron the calculations, for thebar illustrated. showing'the center of gravity forY the upper or head member ofthe bar as being substantially the same` distance above the neutral axis as the-distance of the oo nter of gravity for the lower or foot member of the bar' below the neutral axis. The iigures given indicate these distances to be subftantially the same within a very small fraction. Likewise the novel distribution of metal referred to permits of locating the center lines of stress in the most effective locations and in Apractically balanced relation. This is shown in Fig. 3 of the drawings, wherein for the splice bar illustrated the center line of stress` of the upper or head member of the bar is shown as 1.74 inches above the neutral'axis and the center line of stress for the lower or foot member of the bar as 1.72 inches below the neutral axis, said distances being the same within a very small fraction.

It has been pointed out that the invention contemplates balancing the physical properties of the unsymmetrical zones or parts o t-he bar respectively above and below the 'axis or middle line thereof and in order to malte clear that phase of the invention reference is made to the example ot'V the-zoning of the areas of metal as shown in Fig. 4 or" thc drawings. As illustrated in that figure of the drawings the neutral axis is indicated l by the reference letter 'A and the corresponding zones of metal respectively above and be- 10W the neutral axis are shown as 1, 2 and 3.

ing to the calculations made for these zones the physical properties of upper zone 2 are:

Area .90

i Inertia (I).

statickgnoment '(s).

The physical properties forA lower zone 2 are:

Area. Static moment.

Inertia.

1.29 The physical propertiesfor upper zone 3 are:

Area.

i Static moment.

Inertia,

'The physical properties for lower zone v 3fare:

Inertia.

Static moment.

'Ai-eu.

smti'c mom'ent.

Area.

Inertia.

and the total ofthe physical properties for the' lower zones 2 and 3 are:

Area. Static moment. Inertia.

Thus, it will be seen that within an exceedingly small fraction the effective unsymmetrical parts of the bar respectivelyr above and below the neutral axis are substantially balanced as to their physical properties. Y y

In orderto show how vthis balancing .of the physical properties of the bar above and below the. neutral axis carries out in the full section there is shown in the drawings the calculations made for zones 1 and 2 in the straight web of the bar and when these are' added to the totals above given for the unsymmetrical parts of the bar the physical properties of the whole section above the.I

horizontal neutral axis are:

i Area. Static moment. Inertia.

andi the physical properties for the .whole section below the horizontal neutral "axis are:

Area. Static moment. Inertia.

In the exainples given the horizontal neu-- tral axis has been calculated a trifie below the exact middle line of the section,l namely, at distances of 2.53 from the axis to the extremetop libres and 2.5() from the neutral axis to the extreme bottom fibres, and all calculations given are approximately correct. j'

' Figure4 of the drawings somewhat visualizes the metal .distribution claimed herein.

.It 'shows by dotted lines an old form of splice bar designated by the reference letter O over which is accuratelyl superimposedthenew type splice bar designated by the reference letter N, and in full lines. By comparing these superimposed shapes N and O it will be seen that the web 1.0 of the bar has been materially thinned from its inner side as indicated at 11 `without disturbing the distance of the outerside of the bar from the rail web and in addition to this change Si) I 1n the web constructionthe metal in the innei' vp art 12 of the head 13 of the bar has ,beenY reduced in its vertical depth as will be indicated .by the metal removal designated by the reference number ,14. It will`be seen that the metal removal 11 is carried downwardly and inwardlyy past the web of the.

tremity as at 18 a greater distance beyond the foot flange of the rail than the outward projection of the thick toot langeof the old type bar O. These details in the metal distribution are made proportionately in order to obtain a shape wherein-the areas or zones of metal shall be approximately the same at equal distances respectively above and below the axis or middle line, and whereby the physical properties of said areas and zones of metal will be substantially or approximately the same, with the result of locating the centers of gravity and the center lines of stress at advantageous points in'the bar so as to better resist the strain and stress to whichthe bar is subjected.

A further feature of practical importance in the present invention is the inertia-area ratio established and maintained for the whole section as compared with the inertiaarea ratio established and.- maintained for the unsymmetrical portions of thebar re- 1 spectively above and below its axis of rotation. The vfactor of economy in metal distribution of any sectionv or a portion of a section is represented by the ratio of the momentl Vof inertia to the tarea, that is tia-area ratio ofthe whole section substantiallyA the same the inertia-area ratio of the whole `upper half of the bar above approximately its neutral axis or middle line Aand substantially the same ,as the whole lower half of the bar below approximately its neutral axis or middle line.

While the essentials ofthe invention are best demonstratedby .using the horizontal neutral axis as a basis f or the calculations it is to be understood that I do not limit my invention to the use of' such axis orl that purpose, because some other assumed axis of. rotation may be employed to determine the novel distribution of metal claimed herein without departing. from vthe principles or sacrificing 'any'of `the advantages of the 'inventiom 1. An unsymmet-rical vsplice bar j having unsymmetrical upper and lower vmembers containing zones of metal of approximately the same area atequal distances respectively above and below a neutral axis or middlfA line, the splice bar section having a proportional distribution of metal to dispose the center. lines of stressor pressure of said members respectively at 'substantially the the said line, the splice barisection having a proportional distribution of metal to dispose the center of. gravity of the upper member at substantially the same distance above the axis or middle line as the distance below lower members A said axis lor middle'line of the center of l gravity of the lower member, and also to disposed the center line ofv stress of the upper member at substantially the same distance above the axis or middle line as the distance below said'axis of the center line of stress of the lower member.

8. An unsymmetrical splice bar section having a proportional reducement in metal at the inner side of the web and the upper side yof the foot flange to provide zones'of metal of substantially the same area and physical properties at equal distances respectively above and below the neutral axis.

4.. An unsymmetrical splice bar section having 'a proportional reducement in metal at the inner sideof the web, the underside of the inner hea-d projection and the upper side of the foot flange projected beyond the vertical plane of the outer face of the bar a distance substantially equal to the height of said vertical face, said distribution of metal providing zones of metal of approximately the same area and physical properties at equal distances respectively above and below the neutral axis or middle line.

proportional distribution of metal in its upper and lower portions to provide a sb-` 5. An unsymmetrical splice bar having a of the whole section divided by its area and the inertia area ratios represented by the lmoment of inertia of .the portion above approximately the neutral axis or middle line o the bar divided by its area, and the ino-- ment of inertia ofthe portion of the bar below vthe said axis r middle line divided by its area.

6. An unsymmetrical splice bar having a proportional distribution of metal in the unsymmetrical portions of its upper and lower members to provide a substantial'equivalence l between the inertia-staticratios thereof.

7. An unsymmetrical splice bar having a proportional distribution of metal in its upper and lower unsymmetrical parts toprovide a substantial equivalence between the inertia-static ratios thereof, whereby the centers of stress or pressure of said unsym- Lmetrical parts are disposed atsubsta'ntially the same distance above and below approximately the neutral axis or middle line of the stress or pressure 'o'corresponding portions bar as/a whole. Y are at substantially 'the same distances re- 8. An unsymmetrioal splice bar having a spectively above and below the approxiproportional distribution of metal in the mate neutral axis or middle line of the bar.

5 whole upperA and lower halves thereof and In testimony Whereo I hereunto ax my 15 in the corresponding upper and lower un-f slgnature, vsymmetrical portions to provide a substanon tial equivalence between the yinertia-static BANCROFT G. BRAINE.

10 ratiosthereof whereby the centers of 

